50 pitchers are tied for the best K/9 by a relief pitcher in a season, with 27.00 per nine innings. The first three are Jayvien Sandridge this season and Will Warren and Evan Justice in 2024.
| NAME | K/9 | SEASON | TM | G | W | L | W% | GS | ERA | SO | CG | SHO | SV | IP | H | ER | R | HR | BB | HBP | GF | IBB | TBF | WP | BB/9 | K/BB | HR/9 | K% | BB% | WHIP | BABIP | RA | H/9 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 |  | J. Sandridge | 27.00 | 2025 |  NYY | 1 | 0 | 0 | 0 | 27.00 | 2 | 0 | 0 | 0 | 0.2 | 1 | 2 | 2 | 1 | 2 | 1 | 0 | 0 | 6 | 0 | 27.00 | 1.00 | 13.50 | 33.3 | 33.3 | 4.50 | 27.00 | 13.50 | ||
| 2 | | W. Warren | 27.00 | 2024 | NYY | 1 | 0 | 0 | 0 | 27.00 | 3 | 0 | 0 | 0 | 1.0 | 2 | 3 | 3 | 1 | 1 | 0 | 1 | 0 | 6 | 0 | 9.00 | 3.00 | 9.00 | 50.0 | 16.7 | 3.00 | 1.000 | 27.00 | 18.00 | |
| 3 | | E. Justice | 27.00 | 2024 |  COL | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 2 | 0 | 27.00 | 1.00 | 0.00 | 50.0 | 50.0 | 3.00 | 0.00 | 0.00 | ||
| 4 | | C. Andrews | 27.00 | 2024 | NYY | 1 | 0 | 0 | 0 | 27.00 | 1 | 0 | 0 | 0 | 0.1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 3 | 0 | 0.00 | 27.00 | 33.3 | 0.0 | 3.00 | 27.00 | 27.00 | |||
| 5 | | R. González | 27.00 | 2021 |  CWS | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0.00 | 0.00 | 100.0 | 0.0 | 0.00 | 0.00 | 0.00 | |||
| 6 | | K. Quackenbush | 27.00 | 2021 |  LAD | 1 | 0 | 0 | 0 | 27.00 | 1 | 0 | 0 | 0 | 0.1 | 3 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 4 | 0 | 0.00 | 0.00 | 25.0 | 0.0 | 9.00 | 1.000 | 27.00 | 81.00 | ||
| 7 | | N. Maton | 27.00 | 2021 |  PHI | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0.00 | 0.00 | 100.0 | 0.0 | 0.00 | 0.00 | 0.00 | |||
| 8 | | M. Freeman | 27.00 | 2021 |  CIN | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0.00 | 0.00 | 100.0 | 0.0 | 0.00 | 0.00 | 0.00 | |||
| 9 | | W. Crowe | 27.00 | 2021 |  PIT | 1 | 0 | 0 | 0 | 13.50 | 2 | 0 | 0 | 0 | 0.2 | 1 | 1 | 1 | 0 | 2 | 0 | 0 | 0 | 5 | 2 | 27.00 | 1.00 | 0.00 | 40.0 | 40.0 | 4.50 | 1.000 | 13.50 | 13.50 | |
| 10 | | C. Roe | 27.00 | 2021 |  TBR | 1 | 0 | 0 | 0 | 27.00 | 2 | 0 | 0 | 0 | 0.2 | 1 | 2 | 2 | 0 | 1 | 0 | 0 | 0 | 4 | 0 | 13.50 | 2.00 | 0.00 | 50.0 | 25.0 | 3.00 | 1.000 | 27.00 | 13.50 | |
| 11 |  | F. Peralta | 27.00 | 2021 |  MIL | 1 | 0 | 0 | 0 | 0.00 | 6 | 0 | 0 | 0 | 2.0 | 2 | 0 | 0 | 0 | 3 | 0 | 0 | 0 | 11 | 0 | 13.50 | 2.00 | 0.00 | 54.5 | 27.3 | 2.50 | 1.000 | 0.00 | 9.00 | |
| 12 | | M. Brosseau | 27.00 | 2020 | TBR | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0.00 | 0.00 | 100.0 | 0.0 | 0.00 | 0.00 | 0.00 | |||
| 13 | | J. Beasley | 27.00 | 2020 |  ARI | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 2 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 3 | 0 | 0.00 | 0.00 | 33.3 | 0.0 | 6.00 | 1.000 | 0.00 | 54.00 | ||
| 14 | | T. Kahnle | 27.00 | 2020 | NYY | 1 | 0 | 0 | 0 | 0.00 | 3 | 0 | 0 | 0 | 1.0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 6 | 0 | 9.00 | 3.00 | 0.00 | 50.0 | 16.7 | 2.00 | .500 | 0.00 | 9.00 | |
| 15 | | D. Betances | 27.00 | 2019 | NYY | 1 | 0 | 0 | 0 | 0.00 | 2 | 0 | 0 | 0 | 0.2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 0 | 0.00 | 0.00 | 100.0 | 0.0 | 0.00 | 0.00 | 0.00 | |||
| 16 | | J. Castillo | 27.00 | 2019 |  SDP | 1 | 0 | 0 | 0 | 0.00 | 2 | 0 | 0 | 0 | 0.2 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 4 | 1 | 13.50 | 2.00 | 0.00 | 50.0 | 25.0 | 1.50 | 0.00 | 0.00 | ||
| 17 | | A. Wojciechowski | 27.00 | 2019 |  BAL | 1 | 0 | 0 | 0 | 0.00 | 2 | 0 | 0 | 0 | 0.2 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 1 | 0.00 | 0.00 | 66.7 | 0.0 | 1.50 | 1.000 | 0.00 | 13.50 | ||
| 18 | | J. Gyorko | 27.00 | 2019 |  STL | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0.00 | 0.00 | 100.0 | 0.0 | 0.00 | 0.00 | 0.00 | |||
| 19 | | A. Williams | 27.00 | 2019 |  WSH | 2 | 0 | 0 | 0 | 162.00 | 1 | 0 | 0 | 0 | 0.1 | 5 | 6 | 6 | 2 | 1 | 0 | 0 | 0 | 7 | 0 | 27.00 | 1.00 | 54.00 | 14.3 | 14.3 | 18.00 | 1.000 | 162.00 | 135.00 | |
| 20 | | A. Sampson | 27.00 | 2018 |  TEX | 1 | 0 | 0 | 0 | 54.00 | 1 | 0 | 0 | 0 | 0.1 | 4 | 2 | 3 | 1 | 0 | 0 | 0 | 0 | 6 | 0 | 0.00 | 27.00 | 16.7 | 0.0 | 12.00 | .750 | 81.00 | 108.00 | ||
| 21 | | D. Valencia | 27.00 | 2018 | BAL | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0.00 | 0.00 | 100.0 | 0.0 | 0.00 | 0.00 | 0.00 | |||
| 22 | | J. Bleich | 27.00 | 2018 |  OAK | 2 | 0 | 0 | 0 | 54.00 | 1 | 0 | 0 | 0 | 0.1 | 2 | 2 | 2 | 0 | 0 | 1 | 0 | 0 | 4 | 0 | 0.00 | 0.00 | 25.0 | 0.0 | 6.00 | 1.000 | 54.00 | 54.00 | ||
| 23 | | R. Elias | 27.00 | 2017 |  BOS | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 2 | 0 | 27.00 | 1.00 | 0.00 | 50.0 | 50.0 | 3.00 | 0.00 | 0.00 | ||
| 24 | | D. Magnifico | 27.00 | 2017 |  LAA | 1 | 0 | 0 | 0 | 0.00 | 1 | 0 | 0 | 0 | 0.1 | 0 | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 3 | 0 | 54.00 | 0.50 | 0.00 | 33.3 | 66.7 | 6.00 | 0.00 | 0.00 | ||
| 25 | | W. Cuevas | 27.00 | 2017 |  DET | 1 | 0 | 0 | 0 | 108.00 | 1 | 0 | 0 | 0 | 0.1 | 3 | 4 | 4 | 0 | 0 | 1 | 0 | 0 | 5 | 0 | 0.00 | 0.00 | 20.0 | 0.0 | 9.00 | 1.000 | 108.00 | 81.00 | ||
StatMuse has game-level data for K/9 going back to the 1901 season.
Some of the information used here was obtained free of charge from Retrosheet.
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